1. Field of the Invention
The present invention relates to a process for producing a modified woolen fiber by treating a woolen fiber with silk fibroin to modify it into a silky fiber and to a modified woolen fiber.
2. Description of the Prior Art
Heretofore, to modify a woolen fiber into a silky fiber by treating the woolen fiber with silk fibroin, for example, as shown in FIG. 4, woolen fibers 11 woven into cloth and rolled round a bobbin 12 have been treated in a bath 14 filled with a silk fibroin aqueous solution 13 containing silk fibroin dispersed therein. That is, the woolen fibers 11 have been pulled into the bath 13 by pull-in rollers 15, 16 and lifted by lifting rollers 17, 18 to pass through the silk fibroin aqueous solution 13 in the bath 14 so as to adsorb silk fibroin to the surface of each of the woolen fibers 11.
The silk fibroin aqueous solution 13 is generally prepared by hydrolyzing a silk material such as a cocoon, raw silk, cocoon flocks, raw silk flocks or the like to form a solution, drying it to form fine powders and dispersing them into water again. Silk fibroin fine particles contained in the silk fibroin aqueous solution 13 infiltrate into the woolen fibers 11 together with water by a capillary phenomenon and are adhered to the surface of each of the woolen fibers 11. After the woolen fibers 11 are immersed in the bath 14 for a predetermined time, they are lifted and dried with a hot air drier or the like.
FIG. 1(b) is a diagram of the woolen fiber 11 treated with the above silk fibroin, which shows that silk fibroin fine particles S are separated from one another and sparsely adhered to the surface of each of the woolen fibers. Since the above woolen fibers treated with silk fibroin have a silky feeling and gloss and are inexpensive, they are used in various kinds of fabrics.
However, the silk fibroin treatment of the prior art has such problems as fluctuations in the degree of processing due to lack of uniformity in squeezing and lack of uniformity in dyeing which occurs at the time of dyeing because the silk fibroin fine particles are sparsely and nonuniformly adhered to the surface of the woolen fiber. Since the silk fibroin is physically adhered to the surface of the woolen fiber, the adhesion strength of the silk fibroin is insufficient and the durability thereof is low. Therefore, the adhered silk fibroin falls off from the woolen fiber and the silky feeling and gloss of the woolen fiber are lost when a fabric woven of the woolen fibers is used and washed repeatedly.
To cope with this, there is proposed a technology for improving the adhesion strength of silk fibroin to a woolen fiber by carrying out a silk fibroin treatment using a cation modified silk fibroin solution (Japanese Laid-open Patent Application No. 4-100976). However, as silk fibroin itself is hardly ionized, the adhesion of the silk fibroin is not so improved by carrying out a silk fibroin treatment using the above solution and sufficiently high durability cannot be obtained.
Since the silk fibroin treatment is made on a cloth woven of the woolen fibers, the silk fibroin is not uniformly adhered to the cloth. Therefore, the adhesion of the silk fibroin easily becomes nonuniform.